Dr No[Moderator Omega - Wristscan]
37640
You're right, Erich - I'd forgotten about ref 2984 . . .
. . . employing the hexagonal crown. I once owned the chronometer variant ref 2989 but don't believe they were issued with hexagonal crowns even though they shared cases with 2984.
Here are images of a steel ref 2989 Bill Sohne found . . .
. . . with a typical Seamaster clover crown. This example had a Swiss case, unlike mine which had an American Jonell case.
Best,
Art